Aging in Fits and Starts

December 2025

By Richard Fleming

Photo courtesy of Meg Boulden

Growing old is complicated, an enigmatic journey. I used to think Malcolm Gladwell’s “10,000-hour rule” made sense. He believed it took 10,000 hours of working in a complex field to become an expert. Seems reasonable, right? Well, if old age starts at 65, I have 83,227 hours of experience with this process and I still do not understand it well. Maybe grasping the ins and outs of aging requires a 100,000-hour rule.

One of many confounding aspects of growing old is that it does not happen in a gradual steady way. If aging happened in a linear fashion, we would see a slow continuing decline in our physical and mental functioning as the years pass by. Our aging process would be predictable, unsurprising.

But that is not what happens. Aging unfolds in fits and starts.

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Sometimes a reduction in our function and vitality occurs abruptly because of illness. We may be pushing the grocery cart through the produce section, minding our own business, happy we were able to vote to protect democracy last month, when all of a sudden, boom, we fall to the ground and are paralyzed on our right side from a stroke.

Maybe we are sitting on the couch after eating a healthy dinner of fresh halibut, watching “A Man on the Inside” on television, when we suddenly feel a 30-pound weight on our chest. In the Emergency Department our suspicion that we might have had a heart attack is confirmed.

Or we might be peacefully watering our houseplants when the phone rings. It is our doctor’s office calling, saying she needs to see us this afternoon to discuss the results of our recent x-ray.

These kinds of problems interrupt our prior gradual process of aging with a jolt. We suddenly become five years older. Or ten. And there is no going  back. The smoothly-sloping downward trend we had been following suddenly assumes the shape of a cliff. When this happens it is clear that aging occurs in fits and starts.

Sometimes we are presented with a diagnosis which signals a faster rate of decline, but is not a cliff. Parkinson’s, congestive heart failure, chronic kidney disease – when we learn of having conditions like these, we know we will be facing more challenges sooner. The slope of our aging just became steeper.

Fortunately, through no virtue of my own, I have not yet been given any of these diagnostic accelerants. But of course the phone could ring anytime.

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There is another interesting fits-and-starts phenomenon we oldsters can experience while we’re slip-sliding down the slope. Our bodies go through periods when the aging process accelerates for a while before resuming its prior trajectory. Over the course of a few months, we seem to lose a few years. Medical studies confirm this can happen.

I’ve experienced this phenomenon on a couple of occasions. Several years ago, I noticed over a period of a few months that I was having a harder time squatting down and standing up. At first I thought it was temporary. Maybe I’d strained my knees. But after a few months went by with no improvement, it dawned on me that squatting would be a bit of a challenge from that point on. And to think that activity had been a piece of cake, not long ago.

More recently, I’ve noticed a change in my general energy level. Compared to a few months ago, I get sluggish more easily. I get more tired, even when not doing a lot of activity. My sleep pattern has not changed. I’m eating the same as I always have. There is no recent change in life circumstances. My latest annual physical lab work was normal. But my stamina is not what it was even this past summer.

Maybe you have experienced something similar? Some change that came on over a few weeks to months that marked a break from your previous health status? This is another way that growing old proceeds in fits and starts.

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Scientists are starting to confirm that changes in our metabolism and molecular structures related to aging do not happen in a steady linear fashion throughout life. A 2024 study in Nature Aging looked at various molecular markers of aging in 108 people. The authors found that at around age 44 and again at around age 60, there was a more rapid decline in function, compared to what was otherwise a reasonably steady decrease. Another study in Nature Medicine in 2019 also found occasional periods of more rapid molecular changes, but they identified these changes as happening at around ages 34, 60, and 78.

So the science on this issue is still evolving, as science often does. But it does seem clear that on a biochemical basis, our aging process is not a smooth downward slope.

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So what are the take-home lessons for us old folks? Your guess is as good as mine. I am unaware of anything we can do to avoid the fits and starts of aging. Of course eating well, exercising our bodies and our brains, socializing, getting enough sleep, and avoiding stress can help. But even so, there will be times when it seems the speed of aging is increasing for a period.

When I was starting to plan my post-retirement life, I never thought that at age 74 I would find myself thinking, “Wow, I felt so much healthier at age 72.” I never imagined I would tell myself, “I would love to feel 73 again.”

But nowadays such thoughts do cross my mind.

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